Color code for phono cartridge wiring | Knowledge BaseColor code for phono cartridge wiring. FAQ #3256 Updated March 08, 2018RIAA – Circuit Wiring DiagramsThere are two types of preamplifiers for magnetic phono cartridges. An example of the most common type is the one described in the March 2002 issue of SILICON CHIP has the RIAA equalisation network in the feedback loop.